/*
 * comlan
 */

package com.promfy.util;

public class ConvertUtil {
	/**
     * Convert byte[] to hex string.这里我们可以将byte转换成int，然后利用Integer.toHexString(byte)来转换成16进制字符串。
     * @param src byte[] data
     * @return hex string
     */    
    public static String bytesToHexString(byte[] src){

        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();

    }

    /**
     * Convert hex string to byte[]
     * @param hexString the hex string
     * @return byte[]
     */
    public static byte[] hexStringToBytes(String hexString) {
        if (hexString == null || hexString.equals("")) {
            return null;
        }
        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
            int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
        }
        return d;
    }

    /**
     * Convert char to byte
     * @param c char
     * @return byte
     */
     private static byte charToByte(char c) {
        return (byte) "0123456789ABCDEF".indexOf(c);
    }
     
     public static int indexOf(byte[] data, byte[] pattern) {
 		int[] failure = computeFailure(pattern);

 		int j = 0;
 		if (data.length == 0)
 			return -1;

 		for (int i = 0; i < data.length; i++) {
 			while (j > 0 && pattern[j] != data[i]) {
 				j = failure[j - 1];
 			}
 			if (pattern[j] == data[i]) {
 				j++;
 			}
 			if (j == pattern.length) {
 				return i - pattern.length + 1;
 			}
 		}
 		return -1;
 	}
 	     /**
 	     * Computes the failure function using a boot-strapping process,
 	     * where the pattern is matched against itself.
 	     */
 	private static int[] computeFailure(byte[] pattern) {
 		int[] failure = new int[pattern.length];

 		int j = 0;
 		for (int i = 1; i < pattern.length; i++) {
 			while (j > 0 && pattern[j] != pattern[i]) {
 				j = failure[j - 1];
 			}
 			if (pattern[j] == pattern[i]) {
 				j++;
 			}
 			failure[i] = j;
 		}

 		return failure;
 	}
}